The Behavioral Sciences Research in HIV Infection Training Program at Columbia University provides innovative postdoctoral training in sexuality research applied to HIV prevention science. The Program is grounded in formal training in research methodology, design, and statistical analysis appropriate to our overriding goal of training recent graduates of Ph.D. or M.D. programs to become scholars capable of assuming independent research careers. Our Program emphasizes multidisciplinary training, including matriculation in a specialized track of the M.S. degree in Biostatistics in the Columbia University Mailman School of Public Health. In doing so, we emphasize theoretical rigor, methodological innovation, and practical application in order to provide solutions to the complicated psychological, social, and public health dilemmas posed by the HIV epidemic. Our Training Program, which has been awarded two prior competitive renewals, builds on a record of fifteen years of successful recruitment and training of postdoctoral research Fellows in the behavioral determinants of HIV risk behaviors, models of behavioral change, and other vital mental and public health aspects of HIV infection. The focus in the current funding cycle on intensive training in HIV/AIDS prevention science research with coursework in public health has proven to be successful and is maintained in this proposal. In the next five years of the Training Program, we will continue to maintain a cohort of nine Fellows, each with a three-year appointment. New appointments will be made as Fellows graduate from the Pprogram, to maintain this cohort of nine trainees. The Training Program is built around two overarching structures: a weekly Fellows seminar and a close working relationship between Fellows and their Scientific and Career Mentors, who are experienced senior investigators with histories of independent funding, interdisciplinary collaboration, and mentoring predoctoral or postdoctoral trainees. Fellows undertake four major categories of activities: the mentored research experience, formal academic training, participation in scientific meetings and seminars, and professional skills training. In addition, the Fellowship experience is further enriched by the resources and opportunities offered throughout the Columbia University Medical Center and, more generally, New York City.